This invention relates to and is an improvement of the present co-applicant's prior patent, U.S. Pat. No. 4,491,278, issued Jan. 1, 1985, entitled "COMMINUTOR FOR INLINE FLOW OF SEWAGE", issued to William B. Galanty; and U.S. Pat. No. 4,186,888 issued Feb. 5, 1980.
Both of the foregoing patents were primarily concerned with the provision of improved stationary cage structures and improved rotatable cutting and shredding member for comminutors. As can readily be seen from the foregoing prior art patents little, if any, attention was directed to the need for improvements in the shafts used in such comminutors. However, the need for improvement becomes obvious, when comminutors are used in hostile fluid environments such as sewage sludge processing. The problem becomes more accute when anti frictional bearings are required to facilitate the rotary efficiency of such devices and the need to protect such bearings with bearing seals.
Therefore, in the prior art it is known that shafts of various apparatus may be mounted in such anti-friction bearing arrangements in which an inner ball bearing race is fixed to the shaft and rotates with the shaft while an outer race thereof is fixedly mounted to the support housing. Unfortunately, such bearing arrangements do not provide sufficient sealibility for hostile fluid environments. Attempts have been made to provide pressure seals to one or both sides of the anti-friction bearing and between the fixed support housing and the rotating shaft. Such rotary shaft seals have been complex and the seal's integrity is difficult to maintain or repair. Where fluids acting on the seal arrangements include abrasive materials, such as gritty liquid, sewage sludge, corrosive and other problem fluids, they tend to work their way into the seal arrangements causing deterioration or destruction thereof and its integrity.
More recent prior art fluid pressure rotary shaft seal arrangements have sought to solve some of these rotary shaft seal difficulties. More specifically, in U.S Pat. No. 4,253,713, issued Mar. 3, 1981, to Joseph W. Chambers, there is disclosed a rotary seal arrangement which may be characterized by an annular bushing which rotates with the shaft an annular rotating seal race, an annular resilient seal sleeve. These various parts wear, requiring their replacement. The part subjected to wear include the major bearing and seal housing components. Maintenance down time is relatively high and replacement of parts is acheived with considerable difficulty.
In another related prior art device, U.S Pat. No. 4,482,194, issued Nov. 13, 1984, issued to Joseph W. Chambers, Sr., there is characterized a replaceable wear sleeve cartridge fixedly mounted to a housing bore carrying an internally fixed race of an anti-friction bearing and a static seal race. The wear sleeve cartridge defines a labyrinth preseal bushing fixed to the shaft, the basic elements of a labyrinth preseal and additional resiliency couples through a seal wedge, a rotating race whose end face is both fluid pressure and resiliently biased against the end face of the annular static seal race. The object of this prior art seal sleeve shaft device is the minimize the number of parts and the maintenance down time by the use of a replaceable cartridge sleeve which bears the wear during shaft seal usage. However, it still requires the apparatus to be inoperable during down time repairs.
Accourdingly, it is an object of the present invention to provide a unique rotary seal shaft combination in which a shaft member and a rotary shaft seal with labyrinth bushing member are all self contained entirely within a completely detachable replaceable cartridge device.
A further object of the present invention is to provide a replaceable cartridge device in which gritty liquid, sewage sludge, corrosive and other problem liquids which may become trapped within the labyrinth seal arrangement can be readily removed through outlets provided in the cartridge housing while the apparatus to which the cartridge is connected is in operation.
Yet another object of the invention is to provide such a replacement cartridge which is detachable from the apparatus for exchange and replacement purposes to substantially minimize the down time of the apparatus and enable such replaced device to be repaired at a remote site.
Still another object of the invention is to provide rotation torsion means along an axis of a comminuting shredder axially disposed rotatable member by the use of two replaceable cartridge devices.
While another object of the invention is to provide a two unit interdependent shaft arrangement for an apparatus wherein each unit may be connected or disconnected independent of the other unit for replacement.